Basic Sciences: Section 1 Bone Flashcards
Endocrine effects on bone healing:
Cortisone
Negative, decreased callus proliferation
Endocrine effects on bone healing:
Calcitonin
Positive(?), Unknown
Endocrine effects on bone healing:
TH, PTH
Positive, Bone remodeling
Endocrine effects on bone healing:
GH
Positive, increased callus formation
Stages of graft healing
- Inflammation, chemotaxis
- Osteoblast differentiation
- Osteoinduction
- Osteoconduction
- Remodeling, continues for years
Under optimal stability what type of frature healing takes place?
Intramembranous ossification
Under instability what type of frature healing takes place?
Enchondral ossification
Under extreme instability what type of frature healing takes place?
Pseudoarthrosis
Three histologic phases of distraction osteogenesis?
- Latency Phase, 5-7 days, no distraction
- Distraction Phase, 1mm/day, 1 inch/month
- Consolidation Phase, 2x longer than distraction phase
Dietary requirment of Calcium in children?
600 mg/day
Dietary requirment of Calcium in adolescents and young adults (10-25)?
1300mg/day
Mechanism of PTH
- cAMP
- decreased serum calcium stimulates Beta-2 receptors to release PTH.
Mechanism of Calcitonin
- Increased serum Ca cause secretion of Calcitonin by parafollicular clear cells of the thyroid gland
- Controlled by Beta-2 receptors
- Inhibits osteoCLAST resorption
- decreases serum Ca
Hypercalcemia symptoms
- Polyuria
- Polydypsia
- Kidney stones
- Excessive bony resorption
- CNS effects - confusion, stupor, weakness
- Constipation
Primary hyperparathyroidism
- Overproduction of PTH (parathyroid adenoma MC)
- Increased osteoclastic resorption
- High Ca, PTH, Alk phos, and urinary phos
- Low serum phos
- Brown tumors
Pseudohypoparathyroidism (PHP)
- PTH receptor abnormality, PTH has no effect - blocked by cAMP pathway or lack of cofactors (Mg)
- PTH is normal or high
- Low Ca, High Phos
- Genetic disorder
Albrights hereditary osteodystrophy
- Form of pseudohypoparathyroidism
- PTH receptor abnormality
- Short 1st, 4th, 5th metacarpals/tarsals (brachydactyly)
- Exostosis
- Obesity
- MR
Pseudo-pseudohypoparathyroidism
(pseudo-PHP)
- Phenotype of PHP
- PTH response is normal
Renal osteodystrohpy:
High-turnover
- Kidney disease:
- Decreased phosphate excretion –> very high serum Phos –> decrease Ca –> very high PTH –> SECONDARY HYPERPARATHYROIDISM
- Rugger Jersey spine, osteitis fibrosa, amyloidosis
Renal osteodystrohpy:
Low-turnover
- Normal PTH, elevated Ca and normal Phos
- Due to aluminum deposition in bones which
- decreases mineralization of bone
- decreases proliferation of osteoblasts
- impairs release of PTH from parathyroid glands
- Rugger Jersey spine, osteitis fibrosa, amyloidosis
Sustained increase in PTH (secondary hyperparathyroidism) is caused by which mechanisms?
- Diminished renal excretion of Phosphorus
- Hypocalcemia
- Impaired Calcitriol
- Altered control of PTH release
- Skeletal resistance to PTH